Electric gauge



Dec. 5, 193m F ACON 2,181,960

ELECTRIC GAUGE Filed Dec. 20, 1937 .Patente'dDea51939 UNITED STATES PATENT orrlcs poration of Delaware Application December 20, 1937, Serial NIL-180,718.

Bela-ima- In some gaugesof the prior art the instrument is used to determine the liquid level in a reservoir,

is inparallel with the right hand coil. At the.

. tank-empty position this resistance is zero and the right hand coil is therei'oreshort circuited.

18 The left hand coil alone is active and the arma-' iairemthepointershaftisheld withitsaxis parallel to the left handcoil axis. As the gasoline level in the tank rises the resistance is increased and the right hand coil becomes progressively V I stronger until at the tank-full position the right hand coil is oi. such strength that-the armature is pulled'nearer into parallelism with the coil axis and the pointer iscausedto rotate to the full 7 position on the dial of the gauge. For practical fireasonsthe coils are placed with their axes at an angle oi. about 90, and the pointer rotation 7 material, suitably encased, if necessary, may be 35 exposed to the water cooling system of aninternalcombustion engine. Suitable calibration of the gauge could then be made in temperature degrees. The practical drawback to such a device is the resistance present at the lowest temperaib-ture-to be Thus;-ii' nickel wirewere to be used, its resistance might between, say. 25 ohms at 100 F. and 40 ohms at 212 F. The starting position of the pointer would then he at about two-thirds the scale and the total mnve- 4:; meat would be limited to. am ximatelyone third the scale. 7 'lhepm-poeeortbisinvention-isto balance the magnetlc'circuitinsuchawaythatthefeflect oi this initial rulatance-at-the starting'temperatmeis nulliiled'andthe pointer starts at an l parent zero resistance. This permits the pointer to have the full'60" scale movement. The neutralizlng of .the initial held in the right hand coil is: by a reversed winding on the coll orb an additional reverse coil on the end of the regular right hand coil. Two variations are shown on the accompanying drawing.

Onthe drawing Figure l is an elevational view of the gauge with the dial broken away to show the construction.

Figures 2and 3 are optional circuits of the gauge.

Figure 4 is the circuit of the prior art gauge. Referring to the drawing, Figure 4 shows the circuit of the prior art gauge or differential galvanometer. The battery is indicated at B, and .W is a wire from the battery to the gauge G, which has a right hand cpil RC and a left hand coil LC. The variable resistance is indicated at R, the pointer at P, and the armature at A. PP indicates an iron pole piece to concentrate the flux. The various ground connections are indicated at g.

,In Figure. 4, the right hand coil RC and the resistance R. are in parallel with the left hand coil LC. All the currentpasses through LC all the time and when the resistance R is zero, the coil RC is short circuited to cause the pointer P to assumeth zero position as shown. As the resistance R-increases, more current will pass I through the coil RC and less through the resistance to cause the held about coil RC to increase. This increase in field strength will cause the 'armature to move into greater alignment with the coil RC. 7 The resistance R. corresponds to the resistance at the gasoline tank of an automobile, this resist-' ance being varied according to the change in level oi the gasoline in the tank, the resistance being as zero when the tank is full and maximum when the tank isempty.

The new gauge is indicated as.a.wh ole' at .2.

' The gauge has the left hand electromagnet .or

coil 4 and the right hand electromagnet .or coil 6. The pointer is indicated at 8, being pivotally mounted at It and having the soft iron armature l2 rigidly secured on its shaft. The electromagnets 4 and '6 are energized from the battery l4 having a'wire l6 leading to a common terminal l l to which the ends of the coils 4 and 8 are connected. r

' The right hand coil I is difierent from the corresponding coil of the prior art in that-it has two windingsv 24 and 26 which are opposed to .26 01' the magnet 6, the initial strength of the magneti wouldbesumcientlygreattocansethe pointer 8 to be substantially at mid-position. When thereslstance 28'ds at a minimum,- the strength of the field of the coil 6 is zero due to the opposed windings 24 and .26, thereby enabling the coil 4 to pull the armature l2 and the pointer 8 to the zero scale positionat the extreme left, the position shown in Figures 1, 2, and 3. l

The variable resistance 28 corresponds to the engine unit of a thermoelectric system, the resistance of the unit 28 varying with the temperature, being greater tor higher temperatures, so that as the heat of the engine increases, the resistance 28 will increase to cause -a greater amount of current to flow through the'winding 24, thus to increase the field oi the ma net 6. and" aflect the armature l2 to cause the pointer 8 to swing to the right to indicate increased temperatures The variable resistance 28 may be material having a high temperature coeillcient, such as nickel, iron, or any alloy or material with high temperature-resistance 'coeflicient,

The winding 26 on the coil 6 being of sufiicient strength to reduce the initial 'fiux .of the coil 8 tozer'o,magnet4wiil'pull thepointerBtothe.

zero position. If the reverse winding coil 26 were not used, the initial resistance of the resistance at 28 would be suillciently large to enablethe fiux about the coil 6 to pull the pointer 8- to the right and prevent it from assuming its initial zero position at the extreme left.

Referring to Figure 1, the mechanical construction of the gauge is shown in greater detail. The gauge comprises the casing 32 which houses the frame 34. The frame ismounted on the insulating plate 36 which in turn has a metal rounding plate mounted on the bottom thereof, one of the tabs of the metal plate being indicated at 38. This metal plate is groimded against the casing 32 which in turn is grounded to the frame of theautomobile to complete the circuit. The coils 4 and 6 are mounted on the frame 34,; and coil land coil 26 have one end of their windings connected to their coil cores which are electrically connected to the frame 34, which in turn is connectedto the terminal l8, indicated in dotted outline at the right of the figure. The coil 6 consists of two separate windings 24 and 28, the coil being insulated from the coil bobbin. The coilt and-thewinding 24 of the coilri have one of their ends or leads interconnected by a wire- 39 whichhasalead 40 to ataborfinger 4| connected to the resistance 28. From the resistance 28 the current returns to the battery through ground. The winding 26 and the other end of the winding 24' are connected to a tab or finger 42 which leads toground 20. The coil 4 is adlustably mounted on the frame 34 by means of a metal angle member and the machine screw 52. The coil 6 may, if desired, be similarly mounted. The frame 34 has the ears 44 and 48 on which the dial is mounted, and the third car 48 to mount the pointer I. A pole piece 53 is used to form a l path i'or'and to intensify the flux around the coil The structure of l'lgureii has the same circuit asFigure2 anddiiiersiromthe structureofthe preceding Figures land 2 in that the winding 28' is placed on a separate spool or core and is adjustabiy mounted at the end offl'he coil 24. By adjusting the spool toward or away from the coil 24 a-position can'be'obtained where the initial flux of the elet is zero, which aisnooo pointer 8 to the position shown which is the aer position.

As the resistanceat 28 increases with an increase in temperature,.more current will fiow through winding 24 thereby destroying the magnetic balance with winding 28' and causing the coil 8 to attract the pointer 8 and move it from left to right.

I claim:

1. In an electric gauge having two electromagnets mounted on a frame and arranged in fan shape and having a pointer adapted to move over a scale, said pointer being pivotally mounted at substantially .the intersection of the axes of the electromagnets and having an armature mounted thereon, an opposed winding connected v in parallel with one of the electromagnets and the field of its adjacent electromagnet to substantially zero to cause the other electromagnet to move the pointer to the aero position on the scale, said other electromagnet having at all times a substantially constant external resistance in series therewith.

2. In an electric gauge having two electromagnets arranged in fan shape and having a pointer adapted to move over a scale, said pointer being pivotally mounted at substantially the intersec- 'niounted coaxially therewith at times to reduce tion of the axes of the electromagnets and havadjacent electromagnet to substantially zero to cause the other electromagnet -to move the pointer to the zero position on the scale, said other electromagnet having at all times a subconstant resistance in series therewith.

-3. In an electric gauge having two electromagnets arranged in fan shapeand with a, pointer adapted to move over a scale and being pivotally mounted at substantially the axis of intersection of the center lines of the electromagnets, said pointer being at itszero position when there is substantially no field about one of the electromagnets, said gauge operating to cause the pointer to move across the scale when the resistance in the external circuit increases, means to cause the pointer to assume its zero position when the gauge is interposed in a circuit having a substantially constant. initial external resistance, said means comprising a. plurality of turns of wire wound about the said electromagnet havingthe zero field and creating a field opposite to the field of said electromagnet at times to neutralize the effect of the electromagnet'and there-'' by to enable the other electromagnet to swing the pointer to its zero position.

4. In an electric gauge having two electromagnets arranged in fan shape and with a pointer pointer being at its zero position when thereis substantially no field about one of the electro-.

magnets, said gauge operating to cause the pointer to move across the scale when the resistance in the external circuit increases, means to cause the pointer to assume its zero position when the tially constant. initial external resistance, said means comprising a plurality ofampere turns of uwill enable the left hand magnet 4 to the wire adjacenttoandinaxialalignmentwith'said gage is interposed in a circuit having a substanthereby to enable the left-hand magnet to swing electromagnet having the zero held and creating a field opposite to the field of said electromagnet at times to neutralize the eflect oi the electromagnet and thereby to enable the field of the other electromagnet to swing the pointer to its zero position.-

5. In an electric gauge having a right hand and a left hand electromagnet arranged in fan shape and with a pointer adapted to move over a scale and being pivotally mounted at substantially the axis of intersection of the center lines of the electromagnets, said pointer adapted to be at its zero position when there is substantially no field about the right hand magnet, said gauge operating to cause the pointer to move across the scale when the resistance in the external circuit increases, means to cause the pointer to assume its zero position when thegauge is interposed in' a circuit having a substantially constant initial external resistance, said means comprising a plurality of turns of wire wound about the righthand electromagnet and creating a field opposite to the field of said electromagnet at times to neutralize the eflect oi the electromagnet and Q the pointer to its zero position.

6. In an electric gauge having a right-hand and a left-hand electromagnet arranged in fan shape and with a pointer adapted to move over a scale and being pivotally mounted at substanexternal resistance, said means vcomprising a plu- 'rality of ampere turns of wire adjacent to and in axial alignment with the right-hand electromagnet and creating a field opposite to the field of said electromagnet at times to neutralize the effect of the electromagnet and thereby to enable the field oi the left-hand electromagnet to swing the pointer to its zero position. I

ELBRIDGE I". BACON. 

